This program would adapt a transient forced oscillation method for the measurement of respiratory system impedance in infants. With this method, short duration pressure transients produced by a spark are applied to the lungs via the nose or mouth. By monitoring the reflections of those transients from the lungs with a microphone, and employing Fourier transform techniques with the aid of a computer, measurements over a range of frequencies from one to 10,000 Hertz (Hz) are obtained in less than one second. At low frequencies the results are similar to those obtained with sinusoidal forced oscillation measurements, and can be used to calculate the resistance and reactance. At higher frequencies, the results may be useful in establishing the spatial distribution of respiratory system properties such as cross sectional area and resistance.